Sparking plug for internal-combustion engines



Apr. 17, 1923.

H. F. HOLWORTHY SPARKING PLUG FOR INTERNAL COMBUSTION ENGINES Filed Aug. 9', 1920 FIG. 5.

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Patented Apr. 17, 1923.

UNITED STATES PATENT OFFICE.

HERBERT FLEETWOOD HOLWORTHY, OF SALOP, ENGLAND.

SPARRING PLUG FOB INTERNAL-COMBUSTION ENGINES.

Application filed August 9, 1920. Serial No. 402,180.

1 '0 all whom it may concern:

Be itknown that I, I'lnnnr'n'r Fnnnrwoon HoLwoRrHY, av subject of the King of Great Britain, and a resident of Salop, England, have invented certain new and useful Improvements in Sparking Plugs for Internal- Combustion Engines, of which the following is a specification.

This invention relates to certain improve inents in sparking plugs for internal coinbustion engines, the object of'the invention being to provide a sparking plug with a two part porcelain dielectric which is held to gether by a central electrode, and to provide an apertured dome which encompasses the adjacent ends of the dielectric members, the dome being; associated with the body of the plug and with the external member of the dielectric, the openings through the dome being capped to more efiiciently provide for circulation of air about the jointure of the dielectric members, and to serve as a brace there-for.

In the accompanyimg drawings which show a preferred form of my invention Figure 1 is a longitudinal section of a spark plug made in accord with my invention. Fig 2 is a. side elevation. Fin. 3 is a side elevation of the dielectric members and one of the electrodes. Fig. 4 is a transverse section, taken substantially onthe line A;\r of Fig. 1.. Fig. 5 is a transverse section of I the dome. said section being taken on the line B-B of Fig. 2, and Fig. 6 is a-nend elevation of the thimble or cupped shaped electrode.

Referring to the drawings. the metal body l. of the spark plug is provided at one end with the usual external screw threads for connecting the spark plug" with an engine and at the opposite end the body portion has screw threads 11 formed in the reduced opposite end for attaching thereto a dome l0. Interiorly the body portion of the plug has threads with which engage the threads of a thimble formed with exterior flanges 53 between which are recesses 2*, provided for the reception of a key or spanner used in associatingthe thimble with the body 1. The thimble is of metal and its end is offset-beyond the flanges, and is provided centrally with an opening through which may be passed the end of an electrode 4. In practice the thimble will be made of an appropriate metal and the end 3 which surrounds the aperture will be rounded, as shown. The

interior of the body 1 is formed with a centrally positioned longitudinally disposed opening which is stepped so that the internally threaded wall will be of greater transverse diameter than the space adjoining, in which is seated the head 6* of the dielectric 6, and the opening beyond the seat is of still less diameter thus providing a shoulder or seat for a washer 9.

The sectional dielectrics are preferably made of porcelain and are hollow, the head of the member 6 is rounded and countersunk and the opposite end is recessed. The lower end of the member 5 is similarly recessed to provide a space for the reception of tubular insulation 8 and a washer 7, the sleeve and the washer may be of mica or fiber, and the electrode 4, having a conical intermediate portion and a nut on the threaded end of the electrode provides means for connecting the sections and for attaching a wire thereto, in the usual manner.

The electrical and thermal insulations between the sectional dielectrics prevent the exposed section becoming unduly heated, and to remedy excessive heating and to brace the exposed section, I provide a dome 10, which is screwed upon the body portion of the plug, the cap of the dome being provided with an aperture which permits the passing of the dome about the upper section 5, which is embraced thereby at an intermediate portion the dome bracing such section and rendering the same less liable to fracture by impacts.- The body portion of the dome 10 has therethrough orifices 12 which are overlaid by integral convex projections 14: adapted to deflect air into the dome and out of the same, particularly during travel of the engine or when the plug is positioned where it will be subjected to draftor air in motion, it being desirable to keep the smaller and more fragile element of the dielectric from being heated, more particularly about its joint.

The convex head 6 tends to disseminate tangentially the force or effect of the explosion and the pressure against the head of the encased element of the dielectric will be taken up by the washer 9, which forms a gastight seal.

A two part dielectric may be manufactured more cheaply than one of a single piece, for the reason that the smaller parts are less liable to distortion in the process of manufacture, and in use the breakage is with a s aark point in the usual mannen I so that it may be readily driven there-from,

when the plug is removed from the engine, and in case it should be desired to replace the upper section 5, it may be accomplished by removing the nut and washer and then sliding a new dielectric in place, in case the electrode should slip its enlarged portion will engage with the wall about'the aperture through the thimble 3' and thus be held against dropping into the engine.

1 claim.

1. A spark plug for internal combustion engines comprising a hollow body portion one end thereof being constructed for attachment to an engine and the other end the to maintain a dome, a dielectric comprising two members which are insulated one from other, an electrode which extends through and beyond the dielectrics, a dome associated with the base and with one of the dielectrics to serve as a brace therefor said dome surrounding the jointure between the dielectrics and having therethrough orificeswhich are overlaid by outward projecting concavo-convex open-ended projections.

2. A spark plug comprising a longitudinally apertured body provided with means for attaching the same to an internal combustion engine, dielectrics which are separated from each other by an insulated joint,

an electrode which extends through the dielectrics and the insulated joint, a hollow open-ended member that is adapted to be associated with the body and with a dielectric that extends beyond the insulated joint said member having therethrough air inlet and ex t orlfices which are overlaid by open ended projecting port-ions.

In testimony whereof I a liix my signature in presence of two witnesses.

HERBERT FLE E TWOGD HOLWORTHY.

Witnesses: Y

E. HEGINBOTHAM, A.'J; Dnvms. 

